The invention generally relates to hermetic scroll compressors and more particularly to Oldham couplings therefor.
U.S. Pat. No. 5,306,126 (Richardson), issued to the assignee of the present invention, is incorporated herein by reference and provides a detailed description of the operation of a typical scroll compressor.
Typically, hermetic compressors of the scroll type including a scroll mechanism which receives refrigerant at a suction pressure, compresses the received refrigerant, and discharges the compressed refrigerant at an elevated discharge pressure. Such scroll compressors are typically used in refrigeration, air conditioning and other such systems. The typical scroll mechanism includes an orbiting scroll member and a fixed scroll member, but may in an alternative form comprise co-rotating scroll members. Wraps are provided on each of the scroll members and face and intermesh with each other in an orbiting fashion so as to form pockets of compression during compressor operation.
During compressor operation, pockets of compressed gas within the scroll set act upon the wraps so as to urge them axially apart. Separation of the scroll members results in leakage and inefficient compressor operation. Prior scroll compressor assemblies provide various means for urging the scroll members axially together in an effort to prevent separation of the wrap tips of one scroll member from the interfacing planar surface of the other scroll member. Usually, these means include application of a fluid pressure on a back side surface of one of the scroll members which forces that scroll member toward the other scroll member. Preventing scroll member separation, however, is not simply a matter of applying a pressure on the back side surface of one of the scroll members. As the orbiting scroll member orbits, compressing gas between the interleaved wraps, separation forces are generated which are applied at varying radial distances from the center of the orbiting scroll member. Because these separation forces vary in magnitude and location, oscillating tipping moments are exerted on the orbiting scroll as it orbits relative to the fixed scroll. These oscillating moments can induce wobbling of the orbiting scroll, thereby momentarily separating the wrap tip of one scroll member from the interfacing planar surface of the other scroll member. A tipping moment having a magnitude higher than other tipping moments (herein after the "primary" tipping moment) is exerted on the orbiting scroll in a plane which lies substantially parallel to the crankshaft axis of rotation and substantially perpendicular to the directions in which the Oldham coupling reciprocates with respect to the fixed scroll member. The primary tipping moment is the largest contributing factor in generating undesirable wobbling of the orbiting scroll member. A means of arresting the primary tipping moment's influence on the orbiting scroll member, thereby reducing its contribution to orbiting scroll wobbling, is desirable.
Further, it is an on-going endeavor to reduce the size requirements of refrigerating appliances, air conditioning units and other installation sites of compressor assemblies. Therefore, it is desirable to reduce the package space requirements of compressor assemblies without compromising the refrigerating capacity thereof.